Most of us realise that it's a good idea to use a balun when feeding a balanced antenna from unbalanced feedline. There have been some good articles on this subject, but none that to my mind that fully describe what's going on. Experimentation with a Windom antenna lead me to think more about the fundamental issues, so that I could tackle unwanted feeder radiation in the most effective way. These pages journal what I  discovered along the way.

• What do we mean by 'balanced' and 'unbalanced'?
• Why are baluns necessary?
• What's enough common-mode choking impedance?
• Induced feedline radiation
• Some common-mode choke impedance measurements